High-voltage cable

Abstract

A high-voltage cable for electrostatically charging a coating agent in an electrostatic coating plant is provided. The cable includes a centrally arranged cable core and an electrically insulating jacket which sheaths the cable core. The cable core has a moderate electrical resistance according to the principles of the present disclosure. The cable core includes fibers that form a non-woven fabric, and at least one strip of the non-woven fabric of the cable core is twisted.

The invention claimed is: 
     
       1. A high-voltage cable for charging a coating agent in an electrostatic coating plant, the cable comprising:
 a radially central cable core consisting of a plurality of twisted strips of nonwoven fabric, each strip of nonwoven fabric composed of a plurality of electrically conductive filaments, the cable core having an electrical resistance in the range of 10 kΩ/m-100 kΩ/m; 
 a first electrically insulating jacket layer sheathing the cable core; 
 an electrical shield layer surrounding the first electrically insulating jacket layer, the electrical shield layer having an electrical resistance less than the electrical resistance of the cable core; and 
 a field smoothing element sheathing the cable core at junctions spaced from each other along the cable, the field-smoothing element arranged between the cable core and the first electrically insulating jacket layer, the field-smoothing element lying directly on the twisted strips of the cable core. 
 
     
     
       2. The high-voltage cable of  claim 1 , wherein the filaments each include an electrically insulating material impregnated with electrically conductive carbon, the fabric having a moderate electrical resistance configured for use in an electrostatic coating plant for electrostatically charging a coating agent. 
     
     
       3. The high-voltage cable of  claim 1 , wherein at least part of the filament is made of an electrically conductive plastics material. 
     
     
       4. The high-voltage cable of  claim 1 , wherein the nonwoven fabric strips of the cable core are configured with a coarseness for providing gaps therebetween, respectively, the gaps substantially limiting capillary forces thereat to be substantially insufficient to draw petroleum jelly into the gaps. 
     
     
       5. The high-voltage cable of  claim 1 , wherein the nonwoven fabric strips are twisted sufficiently tightly to be substantially free of gaps between the strips thereof. 
     
     
       6. The high-voltage cable of  claim 1 , wherein the field-smoothing element is made of a plastics material. 
     
     
       7. The high-voltage cable according to  claim 6 , wherein the plastics material is polyolefin. 
     
     
       8. The high-voltage cable of  claim 1 , wherein the field-smoothing element has a moderate electrical resistance configured for use in an electrostatic coating plant for electrostatically charging a coating agent, and the electrical resistance of the field-smoothing element is greater than the electrical resistance of the cable core, and the electrical resistance of the field-smoothing element is less than an electrical resistance of the first electrically insulating jacket layer. 
     
     
       9. The high-voltage cable of  claim 1 , further comprising:
 an electrically insulating outer jacket sheathing the cable core, the first electrically insulating jacket layer and the electrical shield layer. 
 
     
     
       10. The high-voltage cable according to  claim 9 , wherein the outer jacket is made of a plastics material. 
     
     
       11. The high-voltage cable of  claim 1 , wherein the first electrically insulating jacket layer is made of a plastics material, and the cable includes a second electrically insulating jacket layer coaxial to the first electrically insulating jacket layer. 
     
     
       12. The high-voltage cable of  claim 1 , wherein one or more of the plurality of electrically conductive filaments abut the field smoothing element.